G-code Dialects

MapleCAM supports multiple G-code dialects to match different CNC controllers.

Supported Dialects

GRBL

The most common controller for hobby CNC machines. Used by Shapeoko, X-Carve, OpenBuilds, 3018 machines, and many others.

Key characteristics:

Spindle control via M3 S{speed} / M5
Feed rate set with F{rate} on motion commands
Arc commands G2/G3 with I/J offsets
No subroutines or canned cycles

grblHAL

An enhanced GRBL fork with extended capabilities — cutter radius compensation (G41/G42), tool wear compensation, and canned drilling cycles (G81–G89).

Selecting the grblHAL dialect today produces the same G-code as GRBL: MapleCAM doesn't yet emit the grblHAL-only features, so the choice is purely informational. Pick it if your machine runs grblHAL — output will be identical to GRBL but the dialect setting is recorded with the project so future versions of MapleCAM can take advantage of the extra features.

LinuxCNC

An open-source CNC controller running on Linux PCs. Common in more advanced hobby and semi-professional setups.

Key characteristics:

Full G-code implementation including canned cycles
Spindle control via M3 S{speed} / M5
Programs are wrapped with % markers and an O#### program number
Comments use ( comment ) parentheses (MapleCAM emits this style for LinuxCNC; GRBL uses ; comment)
Path blending hint emitted (G64)

Dialect Differences

Feature	GRBL	grblHAL	LinuxCNC
Comment style	`; comment`	`; comment`	`( comment )`
Program markers	none	none	`%` start/end, `O####` program number
Program end	`M30`	`M30`	`M2`
Arc format	`I/J` incremental	`I/J` incremental	`I/J` incremental
Spindle control	`M3`/`M5`	`M3`/`M5`	`M3`/`M5`
Path blending	not emitted	not emitted	`G64` (naive mode)
Tool change	`M6 T{n}` (typically a pause for manual change)	`M6 T{n}`	`M6 T{n}`
Cutter compensation (G41/G42)	not supported by firmware	capable, not emitted today	capable, not emitted today

Choosing a Dialect

Select the dialect in your machine configuration. If you're unsure, GRBL is the safe default — it works with the majority of hobby CNC controllers.

The dialect is used during G-code export. You can change it at any time without regenerating toolpaths.